Device-to-Device (D2D) communication is a new technology that allows directly performing communication between terminals by multiplexing intra-cell resources under the control of a cellular system. It has advantages including improving the utilization rate of system spectrum, reducing battery consumption of the terminal so as to save power of the mobile station, lowering load of the base station of the cellular cell, improving the user fairness of the system, enhancing the quality of network service, consolidating the substructure and providing new services and so on; and it can solve the problem of spectrum resource shortage of the radio communication system to a certain degree.
Under the architecture of the cellular network, the D2D communication can achieve the improvement of the whole system performance by sharing cell resources. If the D2D user is allocated to orthogonal channel recourses, it will not interfere with other users in the cellular network; if the D2D user is allocated to non-orthogonal channel resources, that is, when the D2D user shares the channel recourses with other cellular users, the interference may form between the D2D user and the cellular user, when the interference is critical, it may cause the communication of the cellular user to be interrupted.
As shown in FIG. 1, there is a pair of users D1 and D2 to perform the D2D communication under the cellular network, since the user U1 is far from the D2D user in the beginning, and the cellular network designates the D2D user to share recourses of the U1, at this point the D2D user will not interfere with the cellular network. When the cellular user U1 moves to a position near to the D2D user (or when the D2D user moves so that the D2D user is near to the U1), since the U1 user and the D2D user occupy same recourses, and the interference will occur between the U1 user and the D2D user. If the interference affects the normal communication of the U1 user critically, the cellular network generally will take precedence to ensure the communication of the user U1, then the D2D user may be required to switch to the cellular network to communicate, thereby a phenomenon that the D2D user performs switching frequently may occurs. Due to the unpredictability for the movement of the cellular user and D2D user, therefore the above-mentioned problem is difficult to be avoided.